blockdev: remove bd_block_size_semaphore again

This reverts the block-device direct access code to the previous
unlocked code, now that fs/buffer.c no longer needs external locking.

With this, fs/block_dev.c is back to the original version, apart from a
whitespace cleanup that I didn't want to revert.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 5 insertions, 106 deletions

diff --git a/drivers/char/raw.c b/drivers/char/raw.c
index 0bb207eaef2f..54a3a6d09819 100644
--- a/drivers/char/raw.c
+++ b/drivers/char/raw.c
@@ -285,7 +285,7 @@ static long raw_ctl_compat_ioctl(struct file *file, unsigned int cmd,
 
 static const struct file_operations raw_fops = {
         .read           = do_sync_read,
-        .aio_read       = blkdev_aio_read,
+        .aio_read       = generic_file_aio_read,
         .write          = do_sync_write,
         .aio_write      = blkdev_aio_write,
         .fsync          = blkdev_fsync,
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 1a1e5e3b1eaf..47a949d8a07e 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -116,8 +116,6 @@ EXPORT_SYMBOL(invalidate_bdev);
 
 int set_blocksize(struct block_device *bdev, int size)
 {
-        struct address_space *mapping;
-
         /* Size must be a power of two, and between 512 and PAGE_SIZE */
         if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
                 return -EINVAL;
@@ -126,19 +124,6 @@ int set_blocksize(struct block_device *bdev, int size)
         if (size < bdev_logical_block_size(bdev))
                 return -EINVAL;
 
-        /* Prevent starting I/O or mapping the device */
-        percpu_down_write(&bdev->bd_block_size_semaphore);
-
-        /* Check that the block device is not memory mapped */
-        mapping = bdev->bd_inode->i_mapping;
-        mutex_lock(&mapping->i_mmap_mutex);
-        if (mapping_mapped(mapping)) {
-                mutex_unlock(&mapping->i_mmap_mutex);
-                percpu_up_write(&bdev->bd_block_size_semaphore);
-                return -EBUSY;
-        }
-        mutex_unlock(&mapping->i_mmap_mutex);
-
         /* Don't change the size if it is same as current */
         if (bdev->bd_block_size != size) {
                 sync_blockdev(bdev);
@@ -146,9 +131,6 @@ int set_blocksize(struct block_device *bdev, int size)
                 bdev->bd_inode->i_blkbits = blksize_bits(size);
                 kill_bdev(bdev);
         }
-
-        percpu_up_write(&bdev->bd_block_size_semaphore);
-
         return 0;
 }
 
@@ -459,12 +441,6 @@ static struct inode *bdev_alloc_inode(struct super_block *sb)
         struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
         if (!ei)
                 return NULL;
-
-        if (unlikely(percpu_init_rwsem(&ei->bdev.bd_block_size_semaphore))) {
-                kmem_cache_free(bdev_cachep, ei);
-                return NULL;
-        }
-
         return &ei->vfs_inode;
 }
 
@@ -473,8 +449,6 @@ static void bdev_i_callback(struct rcu_head *head)
         struct inode *inode = container_of(head, struct inode, i_rcu);
         struct bdev_inode *bdi = BDEV_I(inode);
 
-        percpu_free_rwsem(&bdi->bdev.bd_block_size_semaphore);
-
         kmem_cache_free(bdev_cachep, bdi);
 }
 
@@ -1593,22 +1567,6 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
         return blkdev_ioctl(bdev, mode, cmd, arg);
 }
 
-ssize_t blkdev_aio_read(struct kiocb *iocb, const struct iovec *iov,
-                        unsigned long nr_segs, loff_t pos)
-{
-        ssize_t ret;
-        struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
-
-        percpu_down_read(&bdev->bd_block_size_semaphore);
-
-        ret = generic_file_aio_read(iocb, iov, nr_segs, pos);
-
-        percpu_up_read(&bdev->bd_block_size_semaphore);
-
-        return ret;
-}
-EXPORT_SYMBOL_GPL(blkdev_aio_read);
-
 /*
  * Write data to the block device.  Only intended for the block device itself
  * and the raw driver which basically is a fake block device.
@@ -1620,16 +1578,12 @@ ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
                          unsigned long nr_segs, loff_t pos)
 {
         struct file *file = iocb->ki_filp;
-        struct block_device *bdev = I_BDEV(file->f_mapping->host);
         struct blk_plug plug;
         ssize_t ret;
 
         BUG_ON(iocb->ki_pos != pos);
 
         blk_start_plug(&plug);
-
-        percpu_down_read(&bdev->bd_block_size_semaphore);
-
         ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
         if (ret > 0 || ret == -EIOCBQUEUED) {
                 ssize_t err;
@@ -1638,62 +1592,11 @@ ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
                 if (err < 0 && ret > 0)
                         ret = err;
         }
-
-        percpu_up_read(&bdev->bd_block_size_semaphore);
-
         blk_finish_plug(&plug);
-
         return ret;
 }
 EXPORT_SYMBOL_GPL(blkdev_aio_write);
 
-static int blkdev_mmap(struct file *file, struct vm_area_struct *vma)
-{
-        int ret;
-        struct block_device *bdev = I_BDEV(file->f_mapping->host);
-
-        percpu_down_read(&bdev->bd_block_size_semaphore);
-
-        ret = generic_file_mmap(file, vma);
-
-        percpu_up_read(&bdev->bd_block_size_semaphore);
-
-        return ret;
-}
-
-static ssize_t blkdev_splice_read(struct file *file, loff_t *ppos,
-                                  struct pipe_inode_info *pipe, size_t len,
-                                  unsigned int flags)
-{
-        ssize_t ret;
-        struct block_device *bdev = I_BDEV(file->f_mapping->host);
-
-        percpu_down_read(&bdev->bd_block_size_semaphore);
-
-        ret = generic_file_splice_read(file, ppos, pipe, len, flags);
-
-        percpu_up_read(&bdev->bd_block_size_semaphore);
-
-        return ret;
-}
-
-static ssize_t blkdev_splice_write(struct pipe_inode_info *pipe,
-                                   struct file *file, loff_t *ppos, size_t len,
-                                   unsigned int flags)
-{
-        ssize_t ret;
-        struct block_device *bdev = I_BDEV(file->f_mapping->host);
-
-        percpu_down_read(&bdev->bd_block_size_semaphore);
-
-        ret = generic_file_splice_write(pipe, file, ppos, len, flags);
-
-        percpu_up_read(&bdev->bd_block_size_semaphore);
-
-        return ret;
-}
-
-
 /*
  * Try to release a page associated with block device when the system
  * is under memory pressure.
@@ -1724,16 +1627,16 @@ const struct file_operations def_blk_fops = {
         .llseek         = block_llseek,
         .read           = do_sync_read,
         .write          = do_sync_write,
-        .aio_read       = blkdev_aio_read,
+        .aio_read       = generic_file_aio_read,
         .aio_write      = blkdev_aio_write,
-        .mmap           = blkdev_mmap,
+        .mmap           = generic_file_mmap,
         .fsync          = blkdev_fsync,
         .unlocked_ioctl = block_ioctl,
 #ifdef CONFIG_COMPAT
         .compat_ioctl   = compat_blkdev_ioctl,
 #endif
-        .splice_read    = blkdev_splice_read,
-        .splice_write   = blkdev_splice_write,
+        .splice_read    = generic_file_splice_read,
+        .splice_write   = generic_file_splice_write,
 };
 
 int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b33cfc97b9ca..44f288e9726d 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -462,8 +462,6 @@ struct block_device {
         int                     bd_fsfreeze_count;
         /* Mutex for freeze */
         struct mutex            bd_fsfreeze_mutex;
-        /* A semaphore that prevents I/O while block size is being changed */
-        struct percpu_rw_semaphore      bd_block_size_semaphore;
 };
 
 /*
@@ -2379,8 +2377,6 @@ extern int generic_segment_checks(const struct iovec *iov,
                 unsigned long *nr_segs, size_t *count, int access_flags);
 
 /* fs/block_dev.c */
-extern ssize_t blkdev_aio_read(struct kiocb *iocb, const struct iovec *iov,
-                               unsigned long nr_segs, loff_t pos);
 extern ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
                                 unsigned long nr_segs, loff_t pos);
 extern int blkdev_fsync(struct file *filp, loff_t start, loff_t end,